The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Currently, there are more and more needs for products with precision and durability, high reliability and high strength, however, conventional materials and conventional forming and joining technologies may hardly meet design requirements for products. For example, although a magnesium alloy has light weight and may be precisely formed, the magnesium alloy may be poor in strength and easy to crack, and may not be corrosion resistant. Although an aluminum alloy may be precisely formed and may have corrosion resistance and colorful decoration property, however, the aluminum alloy may be low in hardness and may not be wear resistant. Although a zinc alloy may be low in price and easy to form, the zinc alloy may be low in strength, and may not be corrosion resistant. Although a stainless steel may have high strength and high corrosion resistance, the stainless steel may be difficult to precisely form. Even if the stainless steel may be precisely machined, the machining cost is very high, so the stainless steel may be difficult to popularize.
Due to the unordered and uniquely arranged structure of atoms constituting an alloy, an amorphous alloy material, also referred to as metallic glass, may have excellent physical and chemical properties different from those of common crystalline metal materials, for example, high yield strength, high hardness, superelasticity (i.e., high elastic limit), high wear resistance, and high corrosion resistance, so may have broad application prospects.
An amorphous alloy has been first reported in 1960s. Because the critical size (i.e., the largest size to form an amorphous alloy) of the initial amorphous alloy only may reach micron scale, the initial amorphous alloy may be difficult to practically use. In recent years, gradual increase of the critical size of the amorphous alloy makes possible industrial application of the amorphous alloy.
The amorphous alloy has excellent casting performance. For example, the amorphous alloy has low melting temperature like a magnesium alloy, an aluminum alloy, a zinc alloy or a copper alloy, for example, the melting temperature of a rare-earth-based amorphous alloy may be as low as about 300° C. Because the amorphous alloy retains the structural feature of a molten state without phase change, the shrinkage rate of the amorphous alloy may be lower than that of a conventional metal and a plastic. Like a plastic, the amorphous alloy not only has a melting temperature and a glass transition temperature, but also has a large supercooled liquid phase region, so the amorphous alloy may have high flowability and good replicating of the shape and surface of a cast. Meanwhile, without performance difference caused by composition segregation and grain coarsening, the amorphous alloy in a casting state may have excellent mechanical property. The above advantages enable the amorphous alloy to have broad application prospects. For example, the use of an amorphous alloy material to manufacture a frame for an electronic device may solve problems of scratching, destruction under force, and other defects caused by insufficient hardness and strength in a frame made of a conventional metal material. The amorphous alloy material may also be used for manufacturing a structural member with very complex structure and high strength, which may solve large-cutting-amount machining problems created when a steel is used for manufacturing a precise structural member with complex structure and high strength. Meanwhile, the amorphous alloy material may be used for forming a precise micro-gear, which may solve problems of forming difficulty and poor wear resistance of the micro-gear.
However, due to some inherent characteristics of the amorphous alloy, the application of the amorphous alloy material is largely affected. For example, because the hardness of the amorphous alloy is high, when machining, punching and drilling need to be performed on an amorphous alloy article, the process difficulty may be increased, and the life of a cutting tool may be significantly shortened, thus enhancing the production cost. In addition, for an article with very complex structure and a wall thickness not larger than about 0.3 mm, the amorphous alloy article may be difficult to form, which may enhance the production cost to a large extent or even cause the production of the amorphous alloy article not to be carried out. Meanwhile, because the plastic deformation of the amorphous alloy is carried out by forming and extending a low-viscosity region of a shear band, the amorphous alloy generally exhibits very low plastic deformation and appears as a brittle material, which may largely restrict the application of the amorphous alloy in a device for which high safety is required, for example, the application of the amorphous alloy in an article for which drop performance or impact performance are specially required. Meanwhile, the use of various amorphous alloy systems, especially amorphous alloy materials with low amorphous formation ability and low cost, may be largely restricted. In addition, currently, an amorphous alloy is generally constituted by a noble metal, which may be high in material cost; and when the structure of an article is being designed, excellent performance of the amorphous alloy is not required for all the structures of articles. Therefore, how to realize low-cost application of a high-cost material is one difficult problem which needs to be solved.
U.S. Pat. Nos. 5,482,580; 6,818,078 and 6,771,490 disclose methods of joining an amorphous alloy material to other materials. However, in the amorphous alloy composite articles manufactured by these conventional methods, the bonding strength between the amorphous alloy material and other materials is low; the impact resistance of the amorphous alloy composite articles is low; and in the methods disclosed in the above U.S. Patents, it is required that the melting temperature of a pre-formed piece is higher than that of a material to be joined to the pre-formed piece, or the elastic limit of the amorphous alloy material is larger than about 1.5%. Therefore, the use of the amorphous alloy to be joined to other materials may be largely restricted.
Meanwhile, in terms of joining technique, buckling, nut, welding, bonding and other conventional techniques are widely used, which may cause low strength and poor reliability or cause high cost due to process complexity. Even if the insert molding technique is used, due to huge difference of heterogenic materials, the bonding strength is still poor.